Method of using barriers to avoid introducing impurities during crystal ingot casting

Abstract

The invention discloses a method for using barriers to avoid introducing impurities during crystal ingot casting. The method comprises the steps of adding the barriers at the bottom of a crucible; loading a selected seed crystal with good crystal orientation and no mechanical damage into a combustion chamber; conducting charging, vacuuming and ingot casting in sequence. The barriers can prevent crystal ingot raw material liquid from forming a nucleus which causes seed crystal disordered distribution and poor crystal introduction on a crucible silicon nitride coating, effectively avoid the downflow of crystal ingot raw material liquid and a corresponding contact reaction with the crucible, prevent a crucible bottom from sticking, reduce impurities in the crystal ingot casting, shorten a tail red area (low seed area), and improve the yield rate; the unqualified portions of heads and tails of obtained crystal rods are reduced; the method greatly improves the utilization rate of raw materials, educes waste of raw materials, reduces costs and increases production revenue.

Description

technical field [0001] The present application relates to the technical field of crystal preparation, in particular to a method for using a barrier to avoid introducing impurities during crystal ingot casting. Background technique [0002] Solar crystalline silicon material is the most important photovoltaic material. It is used in solar cells and can convert solar energy into electrical energy. In today's shortage of conventional energy sources, solar energy has huge application value. In recent years, the global solar photovoltaic industry has grown rapidly. Solar cells The rapid increase in output has directly driven the sharp expansion of polysilicon demand. Solar crystalline silicon materials include monocrystalline silicon and polycrystalline silicon materials. The high manufacturing cost and complex preparation process of solar-grade crystalline silicon materials are the bottlenecks restricting the development of the photovoltaic industry, which seriously hinders the...

AI Technical Summary

Problems solved by technology

However, the control of this process is complicated, and it is necessary to continue to heat the solidification crucible with electron beams, and at the same time reduce the electron beam current to gradually reduce the temperature so that the ingot is solidified layer by layer from the bottom of the solidification crucible

The production time of a single furnace is long and the equipment is complicated

[0004] At present, in the production of solar-grade crystalline silicon materials, in the semi-molten ingot casting process, seed crystals (SO, S1, REC, etc.) are used to lay the bottom. Nucleation on the SiC coating, resulting in disordered distribution and poor seeding

At the same time, the silicon liquid and the crucible are in solid-liquid contact, and high-concentration impurities diffuse into the silicon ingot, resulting in an increase in impurities in the silicon ingot, an increase in the red zone at the tail, and a decrease in the yield

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